All of these are truly hardy perennials and, especially considering you've hardened them off in a 50-degree room, are ready to go out as soon as your ground is workable.

Joe

I can't address the Scabious or Echinops, but delphs are very cold-hardy and can go outside when there are still light frosts. I'd harden them off better, though, unless you're already past your last frost date. 50 degrees isn't freezing. And they need to get used to full sunlight more gradually.

I used to lose half my delphs at transplant until I started growing them on in 4" pots, putting the seedlings in the pots as soon as the cotyledons (seed leaves) were up and expanded. They don't seem to like having their roots disturbed and are happy to die at transplant unless they have TONS of room in the container they were grown in. But that's just my experience. Perhaps plugs work just fine for everybody else. The climate and wind are a bit of a challenge here.

Jeanne

Jeanne,
Thanks for jarring my memory...I remember doing plugs many years ago of delphs and losing them all...these now are in 804s but I think it is a good idea to maybe put them in four inchers for awhile...and it is windy here also.
I put 12 each of blue, pink and white in 3 quart containers for sale later as perennials, but wanted the rest (20 of each) to add to the field cuts. Guess I'll repot first, then after 2-3 weeks cover with row cover when I put them in the field and hope that helps.
Thanks again.
Ann